Sebastián Beccacece was back in the dugout in Florencio Varela after his ill-fated stint with Argentina and while for 70-odd minutes it looked as though the coach had brought his bad luck back with him, El Halcón eventually saw off El Nacional.
A wet, blustery evening at the Estadio Norberto Tomaghello saw the home side dominate their Ecuadorian visitors for the majority of the game but somehow fail to press home their advantage until late on.
Alexander Barboza had struck the woodwork twice, Nicolás Fernández rounded the busy Johan Padilla only to steer his shot against the post and Christian Almeida thumped a volley off the upright before the deadlock was finally broken.
Fernández, who enjoyed a prolific patch of form during the second half of last season, came off the bench and soon after going close, rifled the ball into the bottom corner from the edge of the box.
The relief was clear after it had looked as though somehow Defensa y Justicia wouldn’t be taking even a slim lead that their commanding performance warranted.
Almost immediately after the lead was doubled when another of Beccacece’s substitutes, Almeida fired through a crowded penalty area and saw his shot deflected past Padilla.
The two-goal lead barely did El Halcón justice and if it had been double that few from Ecuador could have complained. The two sides meet again in two weeks in Quito, where Defensa y Justicia will be confident of progressing to the last 16 but will know that the tie could have been killed off already.